JPS5847064A - Epoxy resin powder paint composition - Google Patents

Abstract

PURPOSE:To provide a quick-curing powder paint compsn. consisting of powdery epoxy resin particles and glass flakes and forming a coating film excellent in flexing resistance, impact resistance at low temperature and cathode peel resistance. CONSTITUTION:The paint compsn. in made from powdery epoxy resin particles (A) consisting of a bisphenol type epoxy resin (e.g., an epoxy resin obtained by condensation of bisphenol A with epichlorohydrin and having an epoxy equivalent of about 700-5,000 and a melting point of about 90-155 deg.C), hardener (e.q., phthalic anhydride, dicyandiamide, adipic hydrazide, 2-methylimidazoline or 2- methylimidazole) and pigment, and glass flakes (B) with an average thickness of 0.5-10mu and an average size of 20-500mu which are used in 5-20wt% of (A). The coating film is in no way inferior to that of conventional powder paint in flexing resistance, shows excellent low temperature impact resistance and cathode peel resistance, and is quick-curing.

Description

[Detailed description of the invention] Regarding.

Conventionally, powder coating of large non-electrical objects such as reinforcing bars and steel pipes, etc., has been carried out at a temperature of 220~. 2IIO
Since repainting cannot be done by preheating to ℃ and painting with electrostatic spray, etc., in order to ensure that the paint film retains its thickness, it is necessary to apply a thick film of about 100μ in % work = degree, and in addition, preheat. It was necessary to apply a type of powder coating that melts in a bath and hardens quickly.

The coating method using this type of powder coating is usually F.
Usion Bonded Coating (F day C)
It is called.

In recent years, large pipeline construction vehicles have been born one after another,
In addition, as they have been installed in cold regions such as Alaska and Sipella, they have been used for conventional extroverted nuclides (2/FB as a solution to overcome the drawbacks of polyethylene lining.
C-Kan's fast-curing epoxy resin powder paint attracted attention and won Yoneyu.

Of course, this type of paint requires fast curing,
In order to withstand harsh usage conditions, the coating film performance is required to be extremely high in terms of low-temperature flexibility, low-temperature impact resistance, hot water immersion resistance, cathodic peeling resistance (corrosion resistance), etc.

In addition, when the object to be coated is a long object such as a 15-meter pipe, the object to be coated is deflected due to its own weight, and accordingly, flexibility of the coating film is naturally required as well.

Therefore, in the above-mentioned powder coatings, compared to the general-purpose Epoquine resin powder coatings, curing accelerators are added in order to shorten the time required, or chemical or ammonium chloride treatment is recommended. In order to satisfy the performance, attempts have been made to change the pigment concentration i. For example, phenolic curing accelerators have been used, trimellitic anhydride has been used as a curing agent, or the violet color of silica pigments has been adjusted.

However, at present, low-temperature impact resistance, cathodic peeling resistance,
A coating film that fully satisfies all properties such as bending resistance has not been obtained.

The present invention was made in view of the above-mentioned current situation,
To provide a fast-curing epoxy resin powder coating composition which has properties such as bending resistance of the coating film that are as good as those of conventional coatings, and which also has extremely excellent low-temperature impact resistance and cathodic peeling resistance. That is, the present invention has the following objects: (A) Powdered epoxy resin particles consisting of a bisphenol type epoxy resin, a curing agent, and a preparation; , average thickness 0. crow flakes having an average size of S~10μ and an average size of 10~SOOμ.

The epoxy resin used in the present invention is bisphenol A
and epichlorohydrin, the yield is about 700-3000 and the melting point is 2>1 about 9 (1
)~/45″clIjA& bisphenol type resin.

Examples of the epoxy resins include Shell Chemical Co., Ltd.'s trade name Ebiot Ioo-tei, f"J 1007, Chipa Co., Ltd.'s trade name Araldite 60g, 6θ9, and 1.Q99.
閤709ri, manufactured by Dow Company, product name DER66+, DER667,
Commercially available products such as bbg@ may be used.

Further, as the curing agent, acid anhydrides such as phthalic anhydride and trimellitic anhydride; dihydrazide such as dihydrazide dihydrazide; imidacillin such as cometely imidazoline and -1 phenyl imidazoline;
Co-methyl imidazole, co-methyl imidazole, -phenylimida! - Can be used as a hardening agent that is solid at room temperature, such as in a mold. These can be used alone or in admixture with one or more oaks.

The above-mentioned epoxy resin and curing agent are mixed with the 7 epoxy groups in the hardening agent and the active hydrogen crab equivalent ratio in the curing agent, and are further colored, rust-prevented, and improve the physical properties of the coating film. Additives such as pigments (coloring pigments, 1M pigments, etc.) and fluid additives to improve the fluidity of the paint film are mixed in advance, melted and mixed at below the hardening temperature, and then crushed and classified. Powdered particles used in the present invention having an average particle diameter of 20 to gθμ are obtained.

The above-mentioned coloring pigments and extender pigments, etc.Q) IO4 materials bv, min & process, bisphenol type epoxy conditions (fat and curing 4jσ) It is preferable to use 20 to 33 parts by weight based on the total amount of 65 to 65 parts by weight of SO. In the present invention, it is essential to use glass flakes with an average thickness of 0.5 to 10 μm and an average diameter of 2O-QOp. It is also used at a rate of 5-.20 electric power for powdered epoxy resin made from other prefecture machining.

In the above range, if the amount of mixed glass flakes is less than the S turtle, it will not be possible to improve the impact resistance and cathode peeling resistance in the low temperature range (-5θ to -60°C), and on the contrary, Koo heavy! Both are unfavorable because if they are used excessively, the flexibility in the low temperature range will decrease.

The epoxy resin powder coating composition of the present invention is produced by tri-blending Moeki's powdered Evokin resin and crow flakes until they become homogeneous! Ill get it.

The composition of the present invention thus obtained has a volume of 2.20 to 2'l
The outside of steel pipes, hook iron pipes, etc. that have been preheated to 0℃h degrees (3) is electrostatically sprayed to a film thickness of about 230-, -00μ, and melts within 5 minutes due to the residual heat of the steel pipes, etc. , cure and form a film. However, since the cooling speed may be fast depending on the vertical shape, size, etc. of the target, post-heating may be performed if necessary.

In the composition of the present invention, when the resin particles melt and flow after starvation, the crow flakes move as a layer on the surface of the resin particles that are melted and flattened, and the moving distance is the largest. Due to its location, it is uniformly distributed within the coating film.
In addition, since the proportion of the particles lining parallel to the object is extremely large, it is thought that the impact resistance and cathodic puncture resistance of the resulting coating are significantly improved.

Thus, the composition of the present invention is industrially extremely useful as a powder coating composition for coating the exterior surfaces of pipelines, buried steel pipes, and the like.

The success of the present invention will be explained below with examples.

Example 1 Epoquin @ qoo-tooo's bisphenol-type compound I Kishijusaka Sg part, trimellitic anhydride 9.3 parts, dicyandiamide [Nel Chemical Table product name Epikure]
71 g of titanium oxide, ys% w titanium, and tal are melted in an extruder, mixed, crushed, and classified to obtain powdered epoxy resin particles with an average particle size of 30 μm.

Next, the powdered epoxy fA fat particles are coated with an average thickness of 2 to S.
The epoxy resin powder coating composition of the present invention was obtained by vibration-mixing crow flakes lOs having an average size of IIooμ.

The obtained set Yft was preheated to 30°C.
After coating on a 0OX//■ Grid Plast steel plate by electrostatic spray coating to a dry film thickness of 30θ to 330μ, post-heating was performed at 230°C for 3 minutes (a comparative test was performed).

Examples 2 to 2 The resin powder coating composition of the present invention was prepared using the valves shown in Table 1 in the same manner as in Example 1, and then test pieces were prepared in the same manner. was obtained and subjected to a comparative test.

M/Table Formulation of Examples U to Q (Unit: 2 parts) 1 Example 31 Example 1 Talc -' tg:
tg ltg Comparative Examples 1 to 3 After obtaining epoxy resin powder perginate compositions of comparative examples in the same manner as in Example 1, using the formulations shown in Table 2, test pieces were prepared in the same manner. The sample was obtained and subjected to a comparative test.

2nd batch Comparative example formulation (unit 2 parts) Table 3 Comparative test result table (note/ ) ASTM (American 5oci
ety for Testing Materials
) Based on G-/'I, use the tip of a hemispherical soft iron of S/g inch as a striking core, place it on a powder coating film, and then apply a 2.3 ~ iron ingot from above. The impact energy value (inner bond) at which impact marks were left on the four membranes was determined by letting it go down the road.

The test was carried out at -so°C.

(Note 2) After applying a strip test piece of 600X-〇 An abnormality in the paint film was confirmed.

The test was carried out at Sθ℃ with a wet layer.

(Note, ?) In accordance with ASTM G-g, a hole with a diameter S■ is drilled on the powder coating surface of Test H to expose the iron base. The surroundings and sides of the test piece are coated with tar-ezokin-based paint, and then paraffin is applied over it to completely insulate it. This test piece was immersed in an aqueous sodium chloride solution, and carbon was used as the counter electrode. Electricity is applied at 00 mV for 30 days (at room temperature).

After energizing, take out the test piece and use a cutter knife to peel off the coating from the 5 m diameter hole, stop at the point where it no longer peels off, and measure the diameter. The coating film was obtained from a resin powder coating composition with no addition of glass flakes (comparison $11/), addition of 25 tatami of crow flakes (comparative example), and addition of scaly iron oxide (comparative example). 3), etc., the results were significantly superior in jt low-temperature impact resistance and cathode peeling resistance.

Claims (1)

[Claims] (1) Powdered Epoquine resin particles consisting of a powder, a suphenolic resin, a curing agent, and a pigment; (B)
A fast-curing epoxy resin powder coating composition comprising crow flakes having an average thickness of 0S to 10μ and an average size of 0 to SOOμ, the weight of which is smaller than the powdered epoxy resin. (A) The fast-curing nixy resin according to claim (1), wherein the curing agent is a mixture of at least one or more selected from acid anhydride, cyandiamide, dihydrazide, imidacillin, and imidazole. Powder coating composition.